PSLE
Zeph had green pencils and silver pencils for sale. He sold 140 green pencils. 30% of the pencils sold were silver.

1. How many green pencils and silver pencils did Zeph sell altogether?
2. He sold 50% of his pencils. 75% of the pencils left unsold were green. How many silver pencils did Zeph have at first?

	Green	Silver	Total	Total in percent
Before	14.5 u	5.5 u	20 u	100%
Change	- 70% - 7 u	- 30% - 3 u	- 100% - 10 u	- 50%
After	75% 7.5 u	25% 2.5 u	100% 10 u	50%

30% = ³⁰₁₀₀ = ³₁₀

Total number of pencils sold = 10 u
Number of silver pencils sold = 3 u

Number of green pencils sold
= 10 u - 3 u
= 7 u

7 u = 140

1 u = 140 ÷ 7 = 20

Total number of pencils sold
= 10 u
= 10 x 20
= 200

(b)
Percent of the pencils left unsold
= 100% - 50%
= 50%

50% of the pencils that were sold = 10 u
50% of the pencils that were left unsold = 10 u

Percent of the pencils left unsold that were green = 75%
Percent of the pencils left unsold that were silver = 100% - 75% = 25%

Number of the pencils left unsold that were silver
= 25% x 10 u
= ²⁵₁₀₀ x 10 u
= 2.5 u

Number of silver pencils that Zeph had at first
= 2.5 u + 3 u
= 5.5 u
= 5.5 x 20
= 110

Answer(s): (a) 200; (b) 110